Remote estimation of crop and grass chlorophyll and nitrogen content using red-edge bands on Sentinel-2 and -3

Estimating foliar nitrogen in Eucalyptus using vegetation indexes

“…Indexes composed of only one wavelength were less susceptible to variation in leaf N concentrations. Nevertheless, as IPP uses a wavelength of high correlation with N concentration (Clevers and Gitelson, 2013), it provided a good estimate in this study ( Figure 2F). …”

“…Among the VIs that used the green region, the CI Green provided less accurate estimations of foliar N concentration ( Figure 2I). However, in other species, these indexes present great potential in estimations of N concentration with accuracy similar to or even higher than VIs based on the red edge (Clevers and Gitelson, 2013;Shclemmer et al, 2013).…”

“…Still, in the blue region, energy absorption can occur from other foliar pigments that might significantly hinder estimation of the chlorophyll content for these wavelengths (Buschmann et al, 1994). Consequently, the best estimates of the chlorophyll content are wavelengths in the green (500 -570 nm) and red regions, in addition to the region known as the red edge (700 -750 nm) (Clevers and Gitelson, 2013;Gitelson et al, 2003;Richardson et al, 2002;Ustin et al, 2009). …”

“…Based on the close relationship between chlorophyll and N, these VIs have been used to estimate N concentration in rice (Tian et al, 2011;Yao et al, 2013), maize (Schlemmer et al, 2013), grasses and potatoes (Clevers and Gitelson, 2013). However, the use of such indexes to estimate N concentration in Eucalyptus is rare in the literature.…”

Efficiency of chlorophyll in gross primary productivity: A proof of concept and application in crops

“…The analysis of chlorophyll efficiency is particularly suitable because non-destructive and remote techniques are readily available to effectively and accurately assess the amount of Chl present at multiple scales, from leaves (Gitelson and Merzlyak, 1997;Gitelson et al, 2006a;Fassnacht et al, 2015;Kira et al, 2015) to entire canopies (Dash and Curran, 2004;Gitelson et al, 2005;Clevers and Gitelson, 2013). Thus, given that limitations due to scaling are reduced, the use of models based on chlorophyll efficiency may allow more direct assessments of plant optimization patterns under different environmental conditions, and in different species/plant functional types.…”